As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Some information handling systems are configured to provide different modes of operation associated with peripheral devices connected to ports on the information handling system. For example, a host information handling system may desire to operate in a first mode under a first set of conditions and a second mode under a second set of conditions when a device is connected to a communication port on the information handling system. One example for this multi-mode operation based upon different operation conditions is the POWERSHARE ports provided on certain DELL portable computer systems.
POWERSHARE ports are configured to charge peripheral devices through their connection to a universal serial bus (USB) port on the information handling system, even when the host system is powered off. For example, using these POWERSHARE ports, users can charge external consumer electronic (CE) devices while the CPU (central processing unit) is in lower power states, such S4 or S5 power states. When the CE is attached to the USB port when the host system is in an S4 or S5 state, the host system detects this event and applies a charging voltage to the USB voltage line. In addition, users do not need to turn on the systems to charge the CE devices. The POWERSHARE port is configured to provide a charging voltage even if the host system is powered off. This feature provides users more portability with their CE devices. When the CE device is plugged into POWERSHARE enabled USB port when the CPU is in a S4 or S5 or off state, the insertion of USB device triggers the USB detection pin and powers up an embedded controller within the host system. The embedded controller then goes into a charging sub-routine and turns on a five volt charging voltage that is applied to the USB voltage line to charge the external device.
FIG. 4 (Prior Art) is a timing diagram 400 for a prior USB charging system associated with this POWERSHARE operation. As with current USB connectors, the POWERSHARE enabled USB port includes four connection lines: VBUS (5 volts), D+ (positive-side differential signal), D− (negative-side differential signal), and GND (ground). When a peripheral device is connected to the USB port of a host information handling system with POWERSHARE while the host CPU is in S4 or S5 power states (or off), the host system generates internal signals 402, 404, 406 and 408 based upon its detection of a device being connected to the USB port. Signal (CHARGER_USB_DET#) 402 represents detection of a USB charge event (active low) when a device is connected to the USB port when the host system is in a condition that will allow charging of an external device through the USB port (e.g., CPU in S4, S5 or off). Signal (EN_CELL_CHARGER_DET#) 404 represents an enable signal to enable power to an embedded controller (active low). An embedded controller power signal (EC PWR) 406 is then generated and applied to an embedded controller within the host system. Once powered by the power signal 406, the embedded controller is configured to apply an enable signal (ENABLE#) 408 to a USB power integrated circuit (IC), which in turn applies a charging voltage (e.g., five volts) to the VBUS line for the USB connection, as represented by signal 410. This USB charging voltage is used to charge the peripheral device connected to the USB port, even when the host system is powered off.
Unfortunately, certain peripheral devices, such as APPLE iPHONE and BLACKBERRY smart phones, require particular conditions on the USB port before they will recognize the connection to a powered-off system as a wall connected power source for charging the device. In particular, these devices look for a DC (direct current) voltage bias on the D+ and D− pins on the USB connector as an indication that the device has been connected to a wall plug. Because of this DC voltage bias operation, information handling systems enabled with POWERSHARE may have difficulty providing the proper DC bias conditions for these peripheral devices to recognize that they should accept an external charging condition from the USB when the system is powered off.
More generally, information handling systems that have been configured to operate under certain expected conditions may have difficulty if those conditions do not meet particular peripheral device configurations. The USB charging conditions addressed above are an example of this need for dual mode operation where a host system hardware has not been configured to address these different peripheral device configurations.